1. Field of the Invention
This invention relates to the field of data storage devices, and more particularly relates to a method and apparatus for emulating a tape backup unit.
2. Description of the Related Art
Advances in applications programs, networking technology, bus architectures, processor technology, hard disk storage capacities and other aspects of today's computing systems have been fueled by business' insatiable need for the information provided by such computing systems. Until fairly recently, storage has been only a small part of the computing infrastructure supporting these advanced computing systems. As data, and the content represented by that data have become increasingly valuable to businesses, however, information storage has emerged as one of the most important aspects of today's data centers. In fact, today's business environment has experienced an explosive growth in data storage requirements, particularly in the primary storage industry (e.g., hard drives and hard-drive-based subsystems). Generally, primary storage typically employs storage technology that is suited for workloads requiring constant, high-volume access to data, such as intensive database activity and frequently-accessed user data. This is in contrast to secondary storage, which is typically used for applications in which infrequent, serial access is required, such as backup for archival storage.
Storage infrastructures have thus undergone considerable changes and advances to keep pace with the rest of the computing equipment now in use. One often overlooked aspect of the storage boom is the effect that this explosion has had on the market for secondary storage (removable media storage), such as tape backup technology.
As storage requirements have changed, tape subsystem technologies have evolved as well, keeping pace with the changes in storage infrastructure technology as a whole. This evolution presents particularly interesting challenges with regard to tape backup technology, because protecting the data stored in today's rapidly-growing storage subsystems is an absolute requirement. Although tape has been around for almost half a century, it remains one of the most cost-effective methods for storing and retrieving data. Tape backup offers the capacity, reliability, and speed necessary for storing and protecting the ever-increasing amount of data generated by businesses. This fact has created an ever growing need for larger and higher-performance tape drives, tape libraries and automation subsystems.
However, tape drives and tape libraries (potentially large, multi-slot (tape) mechanisms in which robotic arms swap tapes in and out of one or more tape drives in the library) are not without their limitations. For developers, the purchase and maintenance of tape drives, and tape libraries in particular, can be expensive and cumbersome. Tape drives and, particularly, tape libraries are slow in comparison to primary storage, potentially limiting the frequency with which such devices can be called into service (for backup, archiving or other purposes). For multi-library installations, slots must be transferred between libraries manually, an obviously labor-intensive operation. In situations where a tape drive or tape library is heavily used, reliability can become an issue, due to the physical mechanisms involved.
What is thus needed is a method and system that address the foregoing limitations. In particular, such a method and system should address the physical limitations of such systems (e.g., speed, reliability, size and the like).